Like many icons of her era, Hepburn's legendary status isn't a testament to her acting range – she invariably spoke in a lock-jaw accent, never put on flab for a role. Her box office appeal was spotty (she had plenty of flops) and she once characterized acting as an idiot's profession. Nevertheless, over six decades she crafted an unconventional, multifaceted persona, one Hollywood never quite knew how to deal with yet ultimately embraced.

Born of East-coast blueblood stock, raised to value intelligence and athleticism – and to speak her mind – Hepburn attended Bryn Mawr College (where she was twice suspended for smoking and breaking curfew) before graduating and making her Broadway debut the same year. Throughout her life, she would continually return to the East Coast and to the stage, never entirely comfortable with the trappings of Hollywood.

Her film career began promisingly enough in 1932 with A Bill of Divorcement where she starred opposite John Barrymore, and her third film, Morning Glory, earned her the first of her four Oscars. In 1938, she teamed with Cary Grant in Bringing Up Baby, a box office disappointment now considered a classic screwball comedy.

But the Hollywood industrial complex and the ticket buying public at large were unsure what to make of Hepburn. She chose unglamorous projects that involved roles-within-roles (a noble disguised as a gypsy, a female con artist disguised as a boy, an old maid posing as her own niece) and had no interest in selling herself as a traditional sex symbol. She eschewed make-up, preferred men's pants and loose sweaters to dresses. She refused most press interviews, could be dismissive in those she granted, and denied autograph seekers. If she could be indifferent toward "the little people" she treated the powerful no better. Hepburn ran afoul of media magnate William Randolph Hearst for her support of muckraking journalist and gubernatorial hopeful Upton Sinclair, and would later make an impassioned anti-HUAC speech penned by blacklisted screenwriter Dalton Trumbo. An acerbic wit, she didn't hold her tongue for anyone – not even the directors, producers and fellow actors she depended on for work.

When a string of flops led a 1938 exhibitors survey to famously label Hepburn "box office poison," RKO studios was only too happy to let her go. For a less determined actor, it might have been a career ender. Instead, Katharine Hepburn used it as an opportunity take the reins, buying the rights to the play Holiday and packaging herself with director George Cukor.

Despite the film's success, Hepburn headed East again to appear in the Broadway production of The Philadelphia Story. When the play she'd commissioned became a success, Hollywood once again came knocking. Two years later, Hepburn met Spencer Tracy and one of Hollywood's great film pairings – and love affairs – was launched. In their films together during the 1940s, the clash between Hepburn's driven, upper-crust persona and Tracy's working-class gruffness made Hepburn-Tracy a bankable screen couple. All that talk about "box office poison" was forgotten.

Had the audience adapted, did the new material suit Hepburn better, or had Hepburn's persona subtly shifted? Fans of the intemperate 'Typhoon Kate' RKO films might argue it was the latter – Hepburn the flighty, flirty, untameable society gal became Hepburn the dedicated, myopic professional who nonetheless yearns for domestication. And if a manly man like Tracy could fall for Hepburn – and vice-versa – maybe she wasn't so threatening, after all.

(Hepburn and Tracy's real-life relationship was even more complicated than any screen variation. Tracy – a devout Roman Catholic – never divorced his estranged wife, and he and Hepburn tried to keep their 25-year affair hidden from the press. From 1962 until 1967, Hepburn put her own film career on hold to care for the ailing Tracy, but didn't attend his funeral out of respect for the family.)

During the 1950s, Hepburn became known as the tough, independent single woman fighting her way in a rugged male-dominated world, this latest incarnation best displayed in The African Queen. As time passed, she was relegated largely to old maid roles and supporting parts in classy (read: boring) stage adaptations. Though in retrospect she's celebrated largely for the RKO and Spencer-Hepburn era films, it's worth noting she won most of her Oscars after the age of 60, suggesting the establishment was more comfortable with her as an accomplished grand dame of Hollywood than the smart-talking, whirling dervish from Connecticut.

In 1999, the American Film Institute named her the greatest screen actress in the history of cinema. Asked about her impending mortality, Hepburn quipped, "Death will be a great relief. No more interviews."